Notch sensitivity of heavily cold-rolled Ni3Al foils

The notch sensitivity of 95% cold-rolled Ni₃Al foils was examined using double U-notched tensile specimens. The foils were found to be essentially insensitive to the presence of the notch. Plastic deformation occurred locally at the notch root to relieve the stress concentration, resulting in the notch insensitivity.     

Stress prediction for polymer blends with various shapes of droplet phase

The excess shear stress after application of large step strains in polymer blend is calculated from observed shapes of deformed droplets in immiscible matrix, based on the Doi-Ohta expression for the interface contribution to the stress. The calculation is made for droplet shapes of flat ellipsoid, rod with end caps, dumbbell and ellipsoid of revolution. The predicted excess relaxation modulus agrees very well with experimental data normalized per one droplet with the volume-averaged radius for a poly(isobutylene)/poly(dimethyl siloxane) blend with narrow distribution of droplet size. Especially, slow stress relaxation in the intermediate stage and faster relaxation thereafter predicted from the rod like and dumbbell shapes are consistent with the experimental data. For a blend of hydroxypropylcellulose solution/poly(dimethyl siloxane) with broad distribution of droplet size, the predicted excess relaxation modulus agrees reasonably well with experimental data by taking account of the size distribution.     

Variable group-delay dispersion equalizer using lattice-formprogrammable optical filter on planar lightwave circuit

The authors report, in detail, an integrated-optic variable group-delay dispersion equalizer based on a lattice-form programmable optical filter. The variable dispersion equalizer consists of an alternating cascade of symmetrical and asymmetrical Mach-Zehnder interferometers. An equalizer with nine symmetrical and eight asymmetrical interferometers is fabricated on a planar lightwave circuit and its dispersion varied step by step from -681 to +786 ps/nm in the operational frequency range of 16.3 GHz. The effectiveness of the equalizer is shown by compensating the dispersion of three different fibers with a single equalizer. The performance of the equalizer is also evaluated and examined by numerical investigations